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Re: Greg Paul is right (again); or "Archie's not a birdy"
Scott Hartman <firstname.lastname@example.org> wrote:
> Birds are a living group of animals (that's sure what Linneaus meant
> when he named them) and their most recent common ancestor (and
> associated descendants). Once we start tossing in taxa further from
> the crown the word becomes more and more misleading. Birds are known
> to have only one working ovary as their primitive condition...is this
> true of Archaeopteryx? Velociraptor? What about the palatine? It was
> assumed (and even described from a poorly preserved version) as having
> the "avian condition" in Archaeopteryx, when better data showed it has
> the more primitive tetraradiate palatine. In fact, outside of
> feathers (which we now know goes far beyond Archaeopteryx) there is
> almost nothing about it that makes it terribly like crown-group birds.
The palatine is a good example. Another obvious and arguably more
insidious example is the "perching foot" of _Archaeopteryx_. It was
assumed that _Archaeopteryx_ had a reversed first toe (=hallux)
suitable for perching, because specimens were preserved with the
hallux in a reversed position, which we now know to be an artifact. A
good look at the first metatarsal of _Archaeopteryx_ revealed that
there was nothing to suggest that this toe could be held in a
retroverted position in life. However, one of the reasons why the
"perching foot" had so much support for such a long time was because
_Archaeopteryx_ was a bird, and modern birds have a reversed hallux.
Like _Archaeopteryx_'s (alleged) ability to fly, its (alleged)
perching ability was propelled by typological thinking.
> I know that some people worry that this will create some sort of
> unspecified havoc with the public ("Congress had to postpone the debt
> ceiling issue today as they took up HB155GA: 'Is Archaeopteryx a
> Bird', which has widespread bipartisan support").
The Tea Party insists that _Archaeopteryx_ is a fake. Also,
_Deinonychus_ is a filthy socialist, because it engages in
(That's a joke - I think.)
> Anyone asking an astronomer why Pluto isn't a planet in effect asking
> "So why IS something a planet?", which in the hands of a good educator
> is pure gold.
Ceres was considered a planet for around fifty years. Not as long as
Pluto, but still a long time. So science has been through this